Independently, and not as an agent of the Government, the contractor will exert its best efforts to snythesize and test irreversible inhibitors of uterine progesterone binding factors. Specifically, the contractor shall: Synthesize derivatives of 19-nor progesterone and 17a -ethynyl-19-nortestosterone substituted in the 6-, 7-, or 17-position by bridging linkages terminating in an arylsulfonyl fluoride; Synthesize these compounds in 200mg-300mg quantities and provide them in 100-200 mg quantities along with criteria of purity to the Contraceptive Development Branch; Test the compounds prepared for their ability to inhibit the binding of progesterone, competitively and irreversibly, by uterine cytosol preparations; and test the compounds for invivo inhibition of uterine uptake of progesterone.